One of these persons in the pic is holding a model of an aircraft in AisAsia colors. I've seen some of these models in such pictures and in my opinion they are perfect models. Now I wonder if normal people who don't work at Airbus or Boeing or Wherever can get these models.

Try the usual sites for big models, sometimes even Ebay. But be Aware, you gotta bring a lot of Money with you often....dont think I am afraid that you are yet "fit" for that with 15, sorry.
Some models tend to cost from few hundred Euros up to a few thousand...